When a report is made of a close approach of an asteroid to the Earth, distances are often specified in Astronomical Units (AU) or possibly in Lunar Distances (LD). The table below relates these two units to the more familiar unit of the kilometre, and also to the Earth's radius (Re).

Note that 1 AU is just under 150 million km, and 1 LD = 0.00256 AU ~ 60 Re.

AU	LD	KM	Earth Radii
0.0001 0.0002 0.0003 0.0004 0.0005 0.0006 0.0007 0.0008 0.0009 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9	0.04 0.08 0.12 0.16 0.19 0.23 0.27 0.31 0.35 0.39 0.78 1.17 1.56 1.95 2.34 2.72 3.11 3.5 3.89 7.78 11.68 15.57 19.46 23.35 27.24 31.13 35.03 38.92 77.83 116.75 155.67 194.59 233.5 272.42 311.34 350.26	14,960 29,920 44,879 59,839 74,799 89,759 104,719 119,678 134,638 149,598 299,196 448,794 598,392 747,989 897,587 1,047,185 1,196,783 1,346,381 1,495,979 2,991,957 4,487,936 5,983,915 7,479,894 8,975,872 10,471,851 11,967,829 13,463,809 14,959,787 29,919,574 44,879,364 59,839,148 74,798,936 89,758,728 104,718,512 119,678,296 134,638,080	2 5 7 9 12 14 16 19 21 23 47 70 94 117 141 164 188 211 234 469 703 938 1172 1407 1641 1876 2110 2345 4690 7034 9379 11724 14069 16414 18758 21103

Material Prepared by John Kennewell. © Copyright IPS - Radio and Space Services.